Handbook of Information Security Management
(Publisher: CRC Press LLC)
Author(s): Hal Tipton and Micki Krause, Consulting Editors
ISBN: 0849399475
Publication Date: 01/01/98

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Recently, we have seen big strides towards consolidating remote network access, with special servers designed to run either remote node or remote control access in a tightly controlled manner. Typical methods for protecting a modem connection that is providing remote access are password protection and call-back. A simple form of the latter approach is for the remote user to dial into the modem at the office, which then hangs up and calls the remote user back. The idea is to prevent people establishing connections from unauthorized numbers, but hackers have found that it is possible to fool the modem at the office into thinking it has dropped the connection, so that the call-back never really takes place. The addition of a password requirement at the time of call-back reduces the chances of this type of hack succeeding.

The call-back approach can be hard to scale when the number of remote users starts to grow, and the cost of long distance calls to all those users starts to add up. An alternative is to provide a toll-free number for remote users to dial into, which is answered by a remote access server. This is a combined hardware and software solution that creates a special node on the network with the ability to receive and authenticate multiple incoming calls. The connection should be authenticated by something stronger than an ordinary password, such as a one-time password generated by a smart card.

For example, modem-maker U.S. Robotics uses the SecurID system on its Total Control Enterprise Network Hub remote access server. To access the server the user enters a PIN followed by the code displayed on the SecurID card issued to that user. The code displayed on the card changes every 60 seconds, in sync with the company’s ACE/Server authentication server at the office. Other options for two-factor authentication (something you know, like a PIN, plus something you have, like a token) include requiring special PCMCIA cards holding encrypted keys to be present in the remote laptop before the connection can be made.

The number of users who dial into the office is bound to increase as companies expand the use of telecommuting and virtual offices. This will continue to provide a possible channel for penetration of internal systems. But improvements in remote access servers supported by two-factor authentication systems have the potential to make such penetration increasingly difficult. Two developments that need to be watched carefully are the shift towards using the Internet for remote access to in-house data bases, and public key-based digital certificates as a means of authentication.

SUMMARY

In less than two decades the microcomputer has risen from the basement workshop and the garage benchtop to become the dominant force in computer hardware. While mainframes and minicomputers continue to anchor many systems, particularly in areas such as online transaction processing, the shift towards client/server solutions based on what are, in essence, microcomputers, shows no signs of abating.

We are only just beginning to come to terms with the information security implications of this phenomenon.20 The process starts with an understanding of the desktop computer environment. Experience has shown that you cannot simply take big-system security practices and impose them on desktop machines. We have to develop security policies and procedures that are appropriate for the desktop. We have to implement those policies and procedures by educating users about security. We might not like it, but the fact is personal computers will never be secure unless the personnel who use them also secure them.

> 20See footnote 7.

There are alternative strategies. For example, you can emasculate the PC and make it an NC, controlled and secured by a server that is treated like a mainframe, even if it is just a beefed up PC. Whether this option will find favor, either in corporate information systems or cubicle-land, remains to be seen.

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